Enrollment UI

Add Enrollment UI client for forwarding CSRs via SCEP to remote PKI system.

- assorted hacks in package, etc
- change getcert to GET
- add GetCert.pm to MANIFEST
- change output of error message
        Change the output of error message to contain all arguments passed
        to exec()
- fix error in specfile for enroll-ui
- read enroller-<shortname>.json, if found
- add Template Toolkit as CPAN prereq
        The Template Toolkit is not used directly by the Enrollment UI,
        but is a nice tool for fixing up configuration files during
        deployment.
enroll-ui: start documentation